sps62 drive pressure readings!

[Forrest Nearing]

combo is: 12v w/ RAYMAC head, ATS manifold, II sps62, AFE race filter, 5" exhaust, 215 pump against the front plug, 215 injectors.



previous owner had a 35psi gauge on the bottom of a 3 gauge pillar to monitor boost on the bottom turbo... it obviously wasn't hooked to anything when I ditched the twins and put the sps62 on. I got another 60psi gauge and hooked it to the exhaust manifold.



I was concerned that maybe w/ the ported head, the turbo might be spinning harder to make the boost...



turbo is untouched from II and if I mash it, will swing to 48psi and settle down to 45... if I roll on it, it'll hit 48psi and stay there... EGT's are between 1200-1250* at full boogie depending on outside temps, etc.



watching the gauges and varying throttle inputs, etc. drive pressure is steadily 5psi LOWER than boost... even at 48psi of boost, drive pressure is right around 43psi!



I need to get my DDP4's in, but haven't had the time or shop space... and frankly, I'm so lazy, and this thing is making just enough power that I don't really have this burning "need" to put them in... on the highway, I'm pulling away from mildly modded trucks as it is.



anyhow, pleasantly surprised at the drive pressure numbers, even approaching 50psi!! I wonder what the drive pressure looked like on my old PDR35-12/S400 combo!

 

[CHolman]

The silver series have even lower drive pressures. Pretty impressive I'd say... What size housing do you have? 12 or 14?

 

[Forrest Nearing]

the "sps" wheel is only available w/ a 14 housing as far as I know...



love this turbo!

 

[CHolman]

love this turbo!

That makes two of us... You should see how it is with the SMARTY and TST R49 stacked... :--) :-laf

 

[Forrest Nearing]

man, I guess I haven't paid attention to EGT's in a while... it's been cool down here lately... today: 58*, low humidity, we're essentially at sea level... at WOT in 6th gear, EGT's will not go over 1125*! LOL! I need more fuel

 

[Forrest Nearing]

update for those subscribed for those searching...



I installed my DDP4's a few days ago... man, DDP4's w/ thin washers beat the snot out of 215's w/ thick washers!!! idle haze is gone, part throttle smoke is all but gone, WOT smoke is probably the same or less.



max boost in 5th is 50psi w/ 55psi of drive pressure...



max boost in 6th is 55psi w/ 50psi drive pressure...



only thing I can come up with is that I've got a hole cut in the cowl from an old Scotty setup... my theory is that in 6th, I've got enough road speed that it's feeding the filter a good supply of semi-pressurized cool air, and it makes the difference



EGT's... in the mid/high 60's, I saw 1400*, at 54* ambient, I saw 1300*, and at 42* ambient down near the coast, 1200* max!!!



oh yeah, I don't know how everyone else has their drive pressure gauges, but mine is just 1/8" copper tube w/ compression that runs over to the driver's cowl, then to 1/8" nylon tube.



twice tonight the DP gauge got stuck... taking it above the level it was stuck on allowed it to drop back down. I'm assuming it's soot buildup? wonder if I can incorporate a vertical soot trap in the thing?

 

[moparguy]

Forrest, I know you travel a bit. But have you been above 7,000' or so with a trailer.



Just wondering if it'll huff or bark when rpm drop below 2,300. Besides egts that can get out of hand when up high, that's one of the other issues I've got with my HTT Hybred.

 

[Jim Fulmer]

max boost in 5th is 50psi w/ 55psi of drive pressure...



max boost in 6th is 55psi w/ 50psi drive pressure...



Sounds like your finally hitting the gate hard enough to open it up further. I'll check these out again too when I'm back up and running with the new ported gate on my 66.



Jim

 

[Forrest Nearing]

Jim, I've noticed that w/ these gates... max presure seems to depend on how you hit it... floor it vs. roll into the fuel... not what I'm used to in the gasser world, but we weren't seeing much over 20psi then either



I haven't had a trailer behind this baby. I'll have some empty performance numbers from 10-12,000ft this summer though